JP6565385B2 - Hologram recording medium - Google Patents

Description

  The present invention relates to a hologram recording medium on which a hologram is recorded.

  Conventionally, various anti-counterfeiting techniques have been applied to prevent forgery of valuable printed matter such as tickets, cash vouchers, and securities. As anti-counterfeiting technologies, various technologies such as anti-copying image lines, holograms, optically changing materials, and latent image patterns are used. Above all, holograms are difficult to duplicate due to the sophistication of the required technology. The applicant has also proposed a forgery prevention technique using a hologram (see Patent Document 1).

JP 2014-92646 A

  When a medium on which a hologram is recorded is optically copied by a copying machine or the like, the pattern of the hologram may be reproduced. In such a copy, the hologram is not completely reproduced, but the pattern itself is recognizable. For this reason, for example, in a dim situation, it may not be possible to instantaneously determine whether it is a copy or an authentic copy. In other words, the copy may be judged to be genuine although it is a copy. This is a problem in situations where it is necessary to perform a large amount of authenticity determination, such as admission checking at a concert venue or the like.

  Accordingly, an object of the present invention is to provide a hologram recording medium capable of making it difficult to represent a picture represented by a hologram even when the hologram is copied by a copying machine.

In order to solve the above problems, in the first aspect of the present invention,
A hologram recording medium having a substrate, a hologram layer on which a hologram is formed, and a printing layer using printing ink,
The print layer is formed so as to overlap the hologram layer, and the print layer is formed using a cold-colored color component.

  According to the first aspect of the present invention, in a hologram recording medium having a substrate, a hologram layer on which a hologram is formed, and a printing layer using printing ink, the printing layer is formed so as to overlap the hologram layer. Since the layer is formed using a cold color component, it is possible to make it difficult to express the pattern represented by the hologram even when the hologram is copied by a copying machine.

  The second aspect of the present invention is characterized in that in the printing layer, the cold color component is realized by a pigment having a high absorption characteristic for light having a wavelength of 550 nm to 800 nm.

  According to the second aspect of the present invention, in the printing layer of the hologram recording medium, the cold color component is realized by the pigment having a high absorption characteristic with respect to light having a wavelength of 550 nm to 800 nm. It is possible to absorb a lot and make it difficult to express the pattern that the hologram expresses even when the hologram is copied by a copying machine.

  The third aspect of the present invention is characterized in that the print layer is printed with a tint block pattern by the cold-colored color component in a range overlapping the hologram layer.

  According to the third aspect of the present invention, since the tint block is printed on the print layer of the hologram recording medium with the cold color component in the range overlapping with the hologram layer, the cold color component is uniformly distributed on the hologram. It is possible to overlap and form.

  According to the present invention, even when a hologram is copied by a copying machine, it is possible to make it difficult to express the pattern represented by the hologram.

It is a figure which shows the hologram recording medium which concerns on one Embodiment of this invention. It is a figure which shows each layer of the hologram recording medium which concerns on one Embodiment of this invention. 1 is a partially enlarged view of a hologram recording medium according to an embodiment of the present invention. It is a conceptual diagram which shows the conventional state in which the taking in of the diffraction light of a hologram is easy with a scanner. It is a conceptual diagram which shows the state by this invention which made it difficult to take in the diffraction light of a hologram with a scanner.

DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the present specification, “parts” and ratios indicating blending are based on mass unless otherwise specified.
<1. Structure of hologram recording medium>
FIG. 1 is a diagram showing a hologram recording medium according to an embodiment of the present invention. 1A is a plan view of the hologram recording medium according to an embodiment of the present invention as viewed from the printed layer forming surface, and FIG. 1B corresponds to the line AA in FIG. FIG.

  In FIG. 1, 1 is a base material, 2 is a hologram layer, 3 is a printing layer. In FIG. 1B, for convenience of explanation, the thickness of each layer is drawn larger than the size of the hologram recording medium (the horizontal direction in the drawing), but the hologram recording medium is in the form of a card or a sheet. In reality, each layer is formed thinner. For example, the size of the hologram recording medium is several centimeters to several tens of centimeters, and the thickness in the vertical direction of the drawing is about several tens of micrometers to several hundreds of micrometers.

  On one surface (the upper surface in the drawing) of the base material 1, a hologram layer 2 is formed in a predetermined region. In the example of FIG. 1, as shown in FIG. 1A, the hologram layer 2 is formed in a rectangular region indicated by shading.

  Further, a print layer 3 is formed so as to overlap the hologram layer 2. In particular, in the example of FIG. 1, the print layer 3 is formed so as to cover the hologram layer 2 as shown in FIG. Further, as shown in FIG. 1A, the print layer 3 is formed in a rectangular region indicated by shading. In the plan view shown in FIG. 1A, the printing layer 3 is located on the front side (front side of the drawing) of the hologram layer 2, but the printing layer 3 is not formed by solid printing, so the lower hologram layer 2 is not formed. Not to hide. As shown in FIG. 1B, the printing layer 3 covers the hologram layer 2, but FIG. 1A shows the positional relationship between the formation area of the hologram layer 2 and the formation area of the printing layer 3. It has become.

  FIG. 2A is a diagram showing only the hologram layer 2 from the upper surface (front side). In the example of FIG. 2A, the hologram layer 2 is formed with a large number of hologram patterns 2a simulating the sun. FIG. 2B shows only the printing layer 3 from the top. In the example of FIG. 2B, a large number of rectangular patterns 3a are printed. The pattern 3a is printed uniformly over the entire area of the printing layer 3 at a predetermined interval, thereby serving as a so-called tint block.

  FIG. 3 is a partially enlarged view of a hologram recording medium according to an embodiment of the present invention. As shown in FIG. 3, since the printing layer 3 is formed so as to overlap the hologram layer 2, the portion of the hologram pattern 2a that overlaps the pattern 3a of the printing layer 3 is hidden. However, the holographic pattern 2a is not concealed in the portion where the pattern 3a is not printed.

<2. Configuration of each layer>
As the substrate 1, various materials can be applied depending on the application. For example, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polyamide resins such as nylon 6, polyolefin resins such as polyethylene, polypropylene and polymethylpentene, vinyl resins such as polyvinyl chloride, polymethyl methacrylate, etc. Examples thereof include cellulose films such as acrylic resin, polycarbonate, cellophane, and cellulose acetate. The substrate 1 may be a copolymer resin containing these resins as a main component, a mixture (including an alloy), or a laminate including a plurality of layers. The substrate 1 may be a stretched film or an unstretched film, but a film stretched in a uniaxial direction or a biaxial direction is preferable for the purpose of improving strength. The substrate 1 is used as a film, sheet, or board formed of at least one layer of these resins. Prior to the application of the hologram layer 2, the substrate 1 is subjected to corona discharge treatment, plasma treatment, ozone treatment, flame treatment, primer (also called an anchor coat, adhesion promoter, or easy adhesive) coating treatment, pre-heat treatment. Further, easy adhesion treatment such as dust removal treatment, vapor deposition treatment, and alkali treatment may be performed. Moreover, you may add additives, such as a filler, a plasticizer, a coloring agent, and an antistatic agent, as needed.

  The hologram layer 2 is formed with a relief hologram made of fine irregularities on the surface of the reflective layer (not shown) located on the substrate 1 side. A hologram pattern 2a as shown in FIG. 2 (a) is expressed by the fine unevenness. The hologram layer 2 is a layer formed by curing a composition containing the following ionizing radiation curable resin with ionizing radiation.

  The ionizing radiation curable resin is (i) an isocyanate having three or more isocyanate groups in the molecule, (b) a polyfunctional (meth) having at least one hydroxyl group and at least two (meth) acryloyloxy groups in the molecule. It is a urethane-modified acrylate resin having ionizing radiation curability, which is a urethane (meth) acrylate oligomer that is a reaction product of acrylates or (C) polyhydric alcohols having at least two hydroxyl groups in the molecule. As a preferable urethane (meth) acrylate oligomer, a photocurable resin disclosed in detail in JP-A No. 2001-329031 is preferable. Specific examples include MHX405 varnish (manufactured by DIC Graphics Corporation, ionizing radiation curable resin product name) and Iupimer UV · V3031 (manufactured by Mitsubishi Chemical Corporation, ionizing radiation curable resin product name).

  The hologram layer 2 is formed by adding the above-mentioned ionizing radiation curable resin and, if necessary, a photopolymerization initiator, a plasticizer, a stabilizer, a surfactant, etc., and dispersing or dissolving in a solvent, What is necessary is just to make it react with ionizing radiation, after apply | coating by well-known coating methods, such as a gravure coat, a comma coat, and a die coat, and drying and shaping a relief. The thickness of the hologram layer 2 is usually about 1 μm to 30 μm, preferably about 2 μm to 20 μm. It may be applied several times.

  Next, a predetermined relief structure that exhibits a light diffraction effect such as a hologram is formed on one surface of the hologram layer 2 and cured. The hologram is a recording of interference fringes due to the interference between the object beam and the reference beam in an uneven relief shape. Holograms include, for example, laser reproduction holograms such as Fresnel holograms, white light reproduction holograms such as rainbow holograms, color holograms utilizing these principles, computer generated holograms (CGH), and holographic diffraction gratings. . The relief shape is a concavo-convex shape, and is not particularly limited, and may have a fine concavo-convex shape such as light diffusion, light scattering, light reflection, light diffraction, etc., such as Fourier transform or lenticular lens. , A light diffraction pattern, and a moth eye. Further, although it does not have a light diffraction function, it may be a hairline pattern, a mat pattern, a line pattern, an interference pattern, or the like that expresses a unique glitter.

  As a method for producing these relief shapes, in addition to holograms and diffraction gratings produced using hologram photographing and recording means, holograms produced using an electron beam drawing device based on optical calculations such as interference and diffraction, A diffraction grating can also be mentioned. Also, a relatively large pattern such as a hairline pattern or a line pattern may be a machine cutting method. These holograms and / or diffraction gratings may be recorded in a single or multiple manner or in combination. These original plates can be prepared by known materials and methods, and usually, laser beam interference using a glass plate coated with a photosensitive material, using an electron beam drawing apparatus on a glass plate coated with an electron beam resist material. An electron beam drawing method for patterning can be applied.

  The relief shape is shaped (also referred to as replication) on the surface of the hologram layer 2. Hologram shaping can be formed by a known method. For example, when recording diffraction gratings or interference fringes of holograms as reliefs of surface irregularities, a master on which the diffraction gratings or interference fringes are recorded in irregularities is pressed. The concave / convex pattern of the original can be duplicated by using it as a mold (referred to as a stamper) and stacking the original on the resin layer and heat-pressing both of them by an appropriate means such as a heating roll.

  The hologram layer 2 is irradiated with ionizing radiation during or after embossing with a stamper to cure the ionizing radiation curable resin. The ionizing radiation curable resin becomes an ionizing radiation curable resin (hologram layer 2) when cured (reacted) by irradiation with ionizing radiation after the relief is formed. The ionizing radiation may be classified according to the quantum energy of the electromagnetic wave, but in this specification, all ultraviolet rays (UV-A, UV-B, UV-C), visible light, gamma rays, X-rays, electrons It is defined as including a line. Accordingly, ultraviolet (UV), visible light, gamma rays, X-rays, or electron beams can be applied as ionizing radiation, but ultraviolet (UV) is preferred. The ionizing radiation curable resin that is cured by ionizing radiation may be added with a photopolymerization initiator and / or a photopolymerization accelerator in the case of ultraviolet curing, and may not be added in the case of electron beam curing with high energy. If an appropriate catalyst is present, it can be cured by thermal energy.

  The pattern of the hologram layer 2 is preferably a quasi-continuous pattern. When creating a press mold (referred to as a stamper) for the pseudo continuous pattern, it is only necessary to match a plurality of small relief plates with high accuracy to make the joints inconspicuous, or to fill the joints with resin. In this way, by using a quasi-continuous pattern, the area can be as large as possible, or preferably the entire surface. Further unique design can be improved by synchronizing or matching with any other printed pattern against a large area or entire surface of the hologram pattern.

  Although not shown, it is preferable to provide a reflective layer on the relief surface of the hologram layer 2 provided with a predetermined relief structure in order to enhance the reflection and / or diffraction effect of the relief. The reflection layer is not particularly limited as long as the reflectance of the hologram layer 2 is higher. The reflection layer may be either a metal reflection layer such as a metal thin film by a vacuum thin film method or a transparent reflection layer.

  In the case of a metal reflective layer, the metal used for the reflective layer is a metal element thin film that has a metallic luster and reflects light, such as Cr, Ni, Ag, Au, Al, etc., and their oxides, sulfides, Thin films such as nitrides may be used alone or in combination. The light-reflective metal thin film can be formed by a vacuum thin film method such as a vacuum deposition method, a sputtering method, or an ion plating method so as to have a thickness of about 10 nm to 2000 nm, preferably 20 nm to 1000 nm. However, it can also be formed by plating. If the thickness of the reflective layer is less than this range, light is transmitted to some extent and the effect is reduced, and if it is more than that, the reflective effect does not change, which is wasteful in cost.

  In the case of a transparent reflective layer, the reflection and / or diffraction effect of the relief is enhanced by providing a transparent reflective layer on the relief surface of the hologram layer 2 provided with a predetermined relief structure. Since the optical refractive index is different from that of the hologram layer 2, it is possible to visually recognize the glitter of the hologram or the like in spite of the lack of metallic luster, so that a transparent hologram can be produced.

Examples of the transparent reflective layer include a thin film having a higher refractive index than that of the hologram layer 2 and a thin film having a lower refractive index. Examples of the former include ZnS, TiO ₂ , Al ₂ O ₃ , and Sb ₂ S. ₃ , SiO, SnO ₂ , ITO, and the like. Examples of the latter include LiF, MgF ₂ , and AlF ₃ . Preferably, it is a metal oxide or nitride, specifically, Be, Mg, Ca, Cr, Mn, Cu, Ag, Al, Sn, In, Te, Fe, Co, Zn, Ge, Pb, Cd , Bi, Se, Ga, Rb, Sb, Pb, Ni, Sr, Ba, La, Ce, Au, or other oxides or nitrides, or a mixture of two or more thereof. Also, a general light-reflective metal thin film such as aluminum can be used when it has a thickness of 200 mm or less. The transparent metal compound is formed on the relief surface of the hologram layer 2 by vacuum such as vapor deposition, sputtering, ion plating, CVD, etc. so that the thickness of the relief layer of the hologram layer 2 is about 10 to 2000 nm, preferably 20 to 1000 nm. It may be provided by a thin film method or the like.

  The hologram layer 2 can be formed on the substrate 1 by various known methods. For example, when using a transfer foil, first, a transfer foil in which a transfer substrate, a release layer, a hologram layer, a reflective layer, and an adhesive layer are laminated is prepared. A protective layer may be provided between the release layer and the hologram layer. The hologram layer 2 is formed on the substrate 1 by transferring the hologram layer and the reflective layer by bonding to the substrate 1 with an adhesive layer using a transfer foil, and separating the transfer substrate and the release layer.

  The print layer 3 is a layer printed with a predetermined pattern as shown in FIG. Since the region where the print layer 3 is formed is a region including the entire region of the hologram layer 2, printing is performed in a pattern rather than solid printing. In other words, the pattern 3a is formed in the print layer 3, and the lower hologram layer 2 is not concealed in portions other than the pattern 3a. The pattern can be printed in various forms, but in this embodiment, so-called tint block printing is performed. The background pattern means the pattern of the ground, and plays a role of the background pattern. Since the tint block printing is performed with the cold color component, the cold color component can be uniformly superimposed on the hologram. As a printing method for forming the printing layer 3, a known printing method such as offset printing, gravure printing, screen printing, inkjet printing, or the like can be used.

  In general, a hologram has a large diffraction efficiency in a long wavelength region. Therefore, when the printing layer 3 formed on the hologram layer 2 does not absorb light in the long wavelength region, the diffracted light from the hologram increases. Therefore, when a warm color pigment that does not absorb light in the long wavelength region is used in the printing layer 3, a phenomenon occurs in which a large amount of diffracted light from the hologram layer 2 is captured when captured by the scanner.

  When a large amount of diffracted light from the hologram layer 2 is captured by the scanner, a large amount of diffracted light from the hologram layer 2 is also captured by the scanner provided in the copying machine, so that the hologram can be copied by the copying machine. . For this reason, in the present embodiment, a contrivance is made so as not to take in much diffracted light from the hologram layer 2. Specifically, the print layer 3 has a function of absorbing long wavelength components by increasing the number of cold color components.

  Basically, any pigment may be used as long as it is a cold color pigment, but a color component that is complementary to the cold color pigment contained in the printing ink is preferred. For example, blue-green ink is used as printing ink. As an example, printing is performed using a printing ink “UV VNL series” manufactured by T & K Toka. The cold color system indicates green, blue, purple, blue-green, indigo, and the like. This can be specified in the 24-color hue ring of PCCS (Practical Color Co-ordinate System). The wavelength of the cold color is preferably 380 nm or more and less than 550 nm. Accordingly, as the printing ink for forming the printing layer 3, a printing ink containing a cold-colored pigment having a high absorption characteristic for light having a wavelength of 550 nm to 800 nm is used.

<3. Example of diffracted light capture>
FIG. 4 is a conceptual diagram showing a conventional state in which the diffracted light of the hologram can be easily taken in by the scanner. A light source 4, a mirror 5, and an image sensor 6 indicate the internal configuration of the scanner. FIG. 4 shows a case where a hologram recording medium having a print layer 3 ′ on which a pattern of only warm color components is formed is read by a scanner. Three arrows from the light source 4 toward the hologram recording medium conceptually indicate the long wavelength component, the medium wavelength component, and the short wavelength component of visible light, respectively.

  In the example of FIG. 4, the pattern of the print layer 3 ′ is formed with only warm color components, and therefore does not absorb much of the long wavelength component. As a result, the long wavelength component reflected by the mirror 5 and taken into the image sensor 6 increases. As a result, the diffracted light from the hologram layer 2 having many long wavelength components is easily taken into the image sensor 6.

  FIG. 5 is a conceptual diagram showing a state according to the present invention in which it is difficult to capture the diffracted light of the hologram by the scanner. FIG. 5 shows a case where the hologram recording medium according to the present embodiment, that is, the hologram recording medium having the printing layer 3 on which a pattern composed only of a cold color component is read by a scanner.

  As shown in FIG. 5, when the print layer 3 includes only a cold color component, the long wavelength component is absorbed by the cold color component. In FIG. 5, the long wavelength component decreased by absorption is indicated by a broken line. Absorption of the long wavelength component makes it difficult for a large amount of diffracted light from the hologram layer 2 to be taken into the image sensor 6. For this reason, it is difficult for the hologram pattern 2a to be expressed in the image obtained based on the light taken into the image sensor 6.

  The preferred embodiment of the present invention has been described above. However, the present invention is not limited to the above embodiment, and various modifications can be made. For example, in the above embodiment, the printing layer 3 is formed so as to cover the entire area of the hologram layer 2, but if it is formed so as to overlap the hologram layer 2, it is not necessarily formed so as to cover the entire area of the hologram layer 2. You don't have to.

DESCRIPTION OF SYMBOLS 1 ... Base material 2 ... Hologram layer 2a ... Hologram pattern 3, 3 '... Print layer 3a ... Pattern 4 ... Light source 5 ... Mirror 6 ... Imaging element

Claims (3)

A hologram recording medium having a substrate, a hologram layer on which a hologram is formed, and a printing layer using printing ink,
The printed layer is formed so as to overlap the hologram layer, and the printed layer is formed using a cold color component ,
The hologram recording medium , wherein the print layer is directly formed on the substrate .   2. The hologram recording medium according to claim 1, wherein in the print layer, the cold color component is realized by a pigment having high absorption characteristics with respect to light having a wavelength of 550 nm to 800 nm. 3. The hologram recording medium according to claim 1, wherein the print layer is printed with a tint block pattern using the cold color component in a range overlapping with the hologram layer. 4.

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